Securing Electric Substations

September 2004
Security Technology & Design Magazine

Protection of critical infrastructure systems has become a major practice area within the security industry. For a number of reasons, electric systems are now under close scrutiny. These reasons include:

One of the key aspects of securing an electric system is to concentrate on the long-lead items. Much discussion centers on the accessibility and consequent vulnerability of the overhead electric lines. These discussions miss the mark and divert needed resources away from the key issues. While loss of a major transmission line will cause disruption in power supply to downstream consumers, the repair time is typically in the order of days. Conversely, the loss of a major transmission substation would have more widespread effects that would be difficult to offset; recovery times could stretch to weeks or months.

At the core of this inherent vulnerability are the long-lead-time substation components such as the transformers. While all utilities stockpile spare items like transformers for recovery from natural disasters, these stockpiles normally do not include the large, one-of-a-kind transformers contained in the larger transmission-level substations. These items normally have a replacement lead time of 12 to 18 months, cannot typically be obtained through cooperative agreements with other utilities, and often have capacities in excess of what can be supported by utility-owned mobile substations. This makes these items Class A assets for electric utility systems.

In general, there are two threats to substations that must be considered.

Standoff Attack
The vulnerability of substation components to damage from hand-held weapons is well known. The primary means of preventing this type of damage involves either removing the ability of the potential adversary to see the target or placing barriers between the substation and the potential adversary of sufficient strength to stop a projectile. The type of projectile (for example, 30.06 military surplus armor-piercing rounds) will determine the construction of the barriers.

Design of the barriers is impacted by at least two factors. First, airflow is required to provide cooling to certain substation components. The barrier must not restrict the airflow or ambient mixing to the point that the air temperature rises above design levels. Second, depending on the configuration of the substation, the barriers may need to be removable to allow for major maintenance or component replacement activities.

Attacks Requiring Access
The other threats of concern are those that require close proximity or access to the substation. Protection against these kinds of attacks relies on essentially the same security approaches used for other kinds of remote facilities. This primarily means lighting, intrusion detection, electronic entry control, and CCTV surveillance/assessment.

Lighting. Lighting is the most cost-effective security measure available. It is relatively common to tie an exterior lighting circuit at remote facilities to an exterior passive infrared motion sensor to turn the lights on when motion is detected. This drastically reduces the operating costs associated with an exterior lighting system at an unmanned facility and also improves the effectiveness of CCTV assessment, if present. Most of the sensors can be tailored to ignore smaller animals such as rabbits.

Intrusion Detection. There are a number of ways to approach intrusion detection at a substation. It is common to see bistatic microwaves used to form a volumetric detection field around the perimeter of the substation. Normally, the microwave transmitter/receivers are installed inside the perimeter fence, which provides some protection against nuisance alarms from blowing debris and animals; however, if the substation has insufficient space for this type of sensor, a number of fence-mounted sensors perform well in this environment. We have also used exterior passive infrared (PIR) sensors to cover key components and approaches. Finally, as discussed in my April article, intelligent video systems may provide a useful tool for larger sites.

Electronic Entry Control. The use of electronic entry control devices such as card readers on vehicular and personal access gates can provide authorized individuals relatively unhindered access to the facility as well as record of the individuals requesting access. They also ensure that when these individuals leave, the facility remains locked. An EECS will provide real-time notification of actual or attempted unauthorized access. In many cases, existing data communications infrastructure such as what might be in place for the supervisory control and data acquisition (SCADA) system can be used for EECS data.

CCTV Surveillance/Assessment. There is clearly an advantage to providing the monitoring security officer a tool whereby he can look at a specific remote facility. CCTV assessment is absolutely necessary if any kind of intrusion detection system sensor is used that would generate an alarm condition. Monitoring a CCTV camera is more cost-effective than dispatching an individual to a remote site.

The difficulty with CCTV systems at remote sites is the transmission of the video data. Again, there are several options available to address this issue. In the past few years, video over telephone lines technology has improved. Video can now be converted to a digital format, or in the case of true digital cameras, sent from the camera as digital. This allows the data to be transmitted over a computer network. The particular solution again is dependent upon many site-specific characteristics.

Response
This leaves the hardest aspect of substation security: response. As with any remote facility, knowing that something is going on is very different than being able to do something about it. Without an effective response component, the installed detection and assessment technology will simply be useful for lessons-learned and forensic purposes.

Response could be provided by a variety of sources such as area service crews. Most electric utilities do not have roving security patrols. The other strong candidate is local law enforcement personnel. A sound corporate security program always includes close liaison and support arrangements with local and state law enforcement agencies. Effectively enlisting the support of these resources may require a corporate effort to communicate the need as well as the development of maps showing the locations of corporate assets. However, the investment will pay off. The perpetrators of substation crime are probably involved in other activities of interest to local authorities. A picture on a substation camera may be just what is needed.

Aside from those utilities with responsibility for nuclear-generating assets, corporate security has traditionally been assigned a relatively low priority. The current security emphasis will push changes in this priority as well as in how centralized generation resources are viewed. Discussions are already underway regarding the different security implications of smaller, localized assets as compared to the current practice. Change may come slowly, but now security is in the equation.

Randall R. Nason, PE is a corporate vice president and manager of the Security Consulting Group at C.H. Guernsey & Co. His experience spans a broad spectrum of the security profession including threat assessment, vulnerability analysis and master plan development through complete system design and construction management.

Randall Nason, PE
Vice President
Manager, Security